Circuit interrupter



May 4, 1943. A. H. BAKKEN CIRCUIT INTERRUPTER Filed May 3l, 1940 E291.

` INVENTOR /7/7 drew 55cm/Ken WITNESSES: 247% 7h@ d? Patented May 4, 1943 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Pennsylvania Application May 3.1, 1940, Serial No. 338,087

1l Claims..

This invention relates t0 circuit interrupters, and more particularly, to improvements in casing structures for housing the contacts and arcextinguishers of circuit interrupters.

It is the usual practice in the design of highvoltage, high-power circuit interrupting apparatus to surround the arc drawing contact structure with a suitable housing which, in addition to its normal function ofproviding a protective enclosure for the contacts also serves to coniine and control the rapidly expanding arc gases resulting from action of the arc upon the arcextinguishing fluid.

rIhe main object of my invention is to provide an improved housing structure for circuit interrupters which is simple in arrangement but capable of withstanding high internal pressure, and which also provides a high degree of insulation when the interrupter is in the open circuit position.

More specically, my invention contemplates utilizing metallic and insulating tubular members in a circuit interrupter housing so arranged that the stresses tending to disrupt the housing are resisted principally by the metallic members.

My invention further contemplates an arrangement of metallic and insulating tubular members in a circuit interrupter housing which relieves the insulating member of all stresses eX- cept those arising by compressing the insulation,

or those arising by subjecting the insulation to compressive shear.

Other objects and advantages relate to the arrangement of the various parts of the circuit interrupting structure, and will appear more fully in the following description when taken in connection with the accompanying drawing, in which:

Figure 1 is a sectional View of a circuit nterrupter embodying the principles of my invention; and

Fig. 2 is a fragmentary sectional View showing a modified form of a circuit interrupter housing.

Referring to the drawing, the reference numeral 3 designates a tubular member of insulating material, substantial upper and lower portions or which have different diameters but are of substantially the same wall thickness so as 'to provide an intermediate portion 5 of greater thickness. cuter and inner annular shoulders at 'l and 9, respectively. The upper portion of the tubular member 3 provided on the interior thereof with a metallic cylindrical section H, the upper The intermediate portion 5 provides end oi which terminates a short distance below 55 the upper end of the member 3. The lcwer end of the section ll has a ange i3 adapted to engage the annular shoulder 9. An annular plate i5 rests upon the upper end of the tubular member 3' and may be bolted to the metallic member il, as shown, so as to provide a support therefor and to draw the ange i3 of the member Il against the annular shoulder 9, thereby placing the upper portion of the tubular member 3 in ccmpression. Secured to the annular member I5 is a casing Vl for housing suitable operating mechanism, generally indicated at I9, 'the purpose of which will hereinafter be more fully described.

The lower portion of the tubular member 3 of insulating material is surrounded by a metallic cylindrical section 2| having a flange 23 at its upper end thereof which is adapted to abut against the annular shoulder 'l of the tubular member 3. The metal section 2l terminates a .short distance above the lower end of the tubular member 3 so as to permit an annular plate member 25 to be bolted to the lower end of the metallic section 2i. so as to bring the plate member 25 into abutting engagement with the lower end of the tubular member 3, and also place the lower portion of the tubular member 3 between the ange 23 and the metallic plate 25, under compression. The annular plate 25 thus supports the metal section 2l and also serves as a support fer a cup-like closure member 21 which may be secured thereto by a plurality oi bolts 29, only one of which is shown and serves to close the lower end of the interrupter housing. The upper end of the interrupter housing is substantially completely enclosed by a partition member 3i forming the base of the casing l?.

rThe interrupter housing as above described is preferably supported by a suitabie framework, only a portion ci which, as represented by a plurality of members 35 of insulating material, is shown. Connection` to the framework in this instance is made by a plurality of support arms 35 secured to the lower meta-l section 2i,

Any suitable contact and arc-extinguishing structures may be employed within the tubular member 3, for example, the mechanism shown and claimed in the application of B. P. Baker and W. Leeds, Serial No. 315,372, filed Januar 24, 1940, and assigned to the assignee of this application. In the aforesaid TE-e er, et al. application and as illustrated herein, the contact structure includes a stationary contact assembly 31 supported by the annular plate TheA contact assembly 3l coacts with e moving contact rod 39 adapted to be actuated into and out of engagement with the stationary contact 31 by the operating mechanism I9. Surrounding the movable contact rod 39 and resting upon the stationary contact assembly 31 is an arc extinguishing structure generally indicated at 4 I The arc extinguishing structure 4l is of the liquid immersed type and preferably comprises a plurality of blocks of insulating material 43 having apertures therethrough for movement of the contact rod 39 and a cylindrical member 45, disposed above the blocks 43, which is yieldingly supported at its upper end by a guide and support member 41. Inasmuch as the contact and arc extinguishing structure does not per se constitute the patentable novelty of the instant application, it is believed that a more detailed description thereof is not needed and the foregoing is sufficient for the purpose at hand.

When the interrupter is in the closed circuit position, as shown in Fig. 1, the electrical circuit therethrough is made from an external terminal 49 through a shunt connection 5I to the moving contact 3S, the stationary contact assembly 31, the annular plate 25, and a second external terminal 53. It will be apparent that upon operating the moving contact 39 to the open circuit position while the interrupter is carrying a load, an arc will be drawn between the stationary and moving contacts so as to generate pressure within the housing as a result of action of the arc upon the arc-extinguishing liquid. The stress from the pressure thus generated, acting radially upon the tubular member 3 of insulating material is substantially relieved by the metallic sections Il and 2 I, respectively, on the inside and outside of the tubular member 3. Pressure due to arcing will also react axially of the tubular member 3 so as to exert a force outwardly against the lower and upper closure members 21 and 3|, respectively. Inasmuch as these closure members are respectively secured to the metal sections 2l and II, these metal sections will be urged outwardly with respect to the ends of the tubular member 3.

Movement, however, of the metal sections II and 2l is prevented due to engagement of the flanges I3 and 23 of the annular shoulders 9 and 1 of the tubular member 3. Thus, on the formation of pressure within the tubular member 3, the intermediate section of that member is subjected to compression and to diagonal shear. The intermediate section 5, however, is made of suiiicient length so that the force required to shear the insulating material disposed between the flanges I3 and 23 is many times greater than that required to fracture the insulating material in a direction at right angles to the axis of the tubular member. t is thus seen that the particular construction above disclosed possesses extreme simplicity and high mechanical strength. The above described arrangement also possesses high insulating properties in that the tubular member 3 of insulating material completely insulates the two metal sections H and 2l from each other when the interrupter contacts 31 and 39 are in the open circuit position, and thus provides the necessary insulation between contacts to withstand the usual open circuit, voltage.

In Fig. 2 of the drawing a slightly modified form of housing structure is shown. In this instance the tubular member 3 of insulating material has an intermediate portion 55 of thickness somewhat greater than the portion 5 previously described. Thus, by maintaining the same general wall thickness of the tubular member 3, in-

creasing the thickness of the intermediate portion as at 55 permits the use of flanges 51 and 53 of greater width than the anges I3 and 23. The flanges 51 and 59 can thereby be made to overlap each other so that a substantial portion at least of the intermediate portion 55 is placed in direct compression when the metal sections I I and 2| are urged outwardly with respect to the tubular member 3.

Although the particular housing structure above described has been shown in connection with a circuit interrupting device of the liquid immersed type, it will be understood that the particular housing structure may also be employed in housing interrupting structures, generally. It is also to be understood that the specific structure shown and described is for the purpose of illustration and that changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. In a circuit interrupter, a casing comprising a pair of tubular metal members disposed in telescopic relation with respect to each other, a tubular member of insulating material disposed between said tubular metal members for insulating one from the other, support means for each of said tubular metal members, said support means bearing against the outer ends of said member oi insulating material and tending to move said metal members apart, and means for securing the inner ends of said metal members to said tubular member of insulating material for holding said metal members against movement.

2. In a circuit interrupter, a casing comprising a pair of cylindrical metal sections disposed in telescopic relation with respect to each other, the overlapping ends of said cylindrical sections having transverse iianges, each of which extends in a direction toward the other section, a cylindrical member of insulating material disposed between said metal sections, said cylindrical member of insulating material having an annular shoulder portion engaging the inner surface of each of said flanges for holding said metal sections against axial movement out of telescopic relation with respect to each other and extending in an axial direction to at least the outer ends of said metal sections to provide a substantial insulating surface along the inner surface of one of said metal sections and along the outer surface of the other of said metal sections.

3. In a circuit interrupter, a casing comprising a cylindrical member of insulating material, said cylindrical member having an intermediate wall portion of greater thickness than its end portions, a pair of tubular metal sections of different diameter, one of which is disposed inside of said member oi insulating material and extends from said intermediate portion to adjacent one end of the casing and the other of which is disposed outside of said member of insulating mate- 4. In a circuit interrupter, a casing comprising a pair of tubular metal members disposed in spaced concentric and partially overlapping relation, the inner ends of said tubular metal members having flanges thereon, a tubular member of insulating material disposed between said tubular metal members, said member of insulating material having an intermediate portion having annular off-set surfaces against which said flanges are adapted to be drawn for holding said metal members against outward axial movement with respect to said member of insulating material, a closure member for each end of said tubular member of insulating material, and means for securing each of said Closure members to a respective one of said pair of tubular metal members for holding said tubular member of insulating material in compression between said closure members.

5. In a circuit interrupter, separable Contact means for establishing an arc, a housing for said contact means comprising a cylindrical casing member of insulating material, a cylindrical metal member surrounding said member of insulating material and extending from one end thereof a substantial distance therealong, a second cylindrical metal member disposed on the inside of said member of insulating material and extending from the other end thereof a substantial distance beyond the inner end of said iirst metal member and a closure member secured to the outer end of each cylindrical metal member, the inner ends of said metal members being provided with flanges, said casing member of insulating material having an intermediate portion in abutting engagement with said flanges for compressively resisting outward movement of said cylindrical metal members and said closure members due to pressure generated within said housing during a circuit interrupting operation.

6. In a circuit interrupter, a pair of tubular metal sections disposed in telescopic relation, a pair of separable contacts disposed within said metal sections, one of said contacts being supported by and connected to the inner one of said metal sections, the other of said contacts being supported by and connected to the outer one of said metal sections, a tubular member of insulating material disposed between said metal sections for insulating said contacts and said sections from each other when the interrupter is in the open circuit position, and a support for the interrupter secured to one of said metal sections.

7. In a circuit interrupter, a pair of tubular metal sections disposed in telescopic relation, a pair of separable contacts disposed within said metal sections, one of said contacts being supported by and connected to the inner one of said metal sections, the other of said contacts being supported by and connected to the outer one of said metal sections, a tubular member of insulating material disposed between said metal sections for insulating said contacts and said sections from each other when the interrupter is in the open circuit position, a support for the interrupter secured to the outer metal section, and terminal means including said outer metal section for making an external circuit connection to said interrupter.

8. In a circuit interrupter, separable contact structure, a housing for said contact structure comprising a tubular member of insulating material, a pair of tubular metal members one of which is disposed within and the other around said tubular member of insulating material, said metal members extending respectively from substantially the outer ends of said member of insulating material toward each other and terminating in partially overlapping relation at their inner ends, means securing the inner ends of said tubular metal members to said member of insulating material to hold said tubular metal members against outward movement, a closure member disposed in engagement with each end of said tubular member of insulating material, and means securing each closure member to its respective tubular metal member for drawing said closure members into engagement with said tubular member of insulating material.

9. In a circuit interruptor, arc terminal means between which an arc is established, a casing in which said arc is established comprising a pair of tubular metal members each substantially at the potential of one arc terminal and disposed in spaced concentric and partially overlapping relation, the inner ends of said tubular metal members having interlocking flanges thereon, a tubular member of insulating material having a portion lling the interflange space and other portions extending axially in each direction to a point adjacent the outer ends of said tubular metal members, and means urging said tubular metal members outwardly to place said filling portion of said tubular member of insulating material under compression.

10. In a circuit interrupter, arc terminal means for establishing an arc, a casing defining a chamber within which the arc is established, said casing including a tubular member of insulating material, a tubular metal member lining said tubular member of insulating material internally from adjacent one end of the chamber to adjacent the middle thereof only, a second tubular metal member lining said tubular member of insulating material externally from adjacent the other end of the chamber to adjacent the middle thereof only, each of said tubular metal members being substantially at the p0- tential of one of said arc terminal means, and each of said tubular metal members having means for gripping said tubular member of insulating material adjacent the middle thereof.

11. In a circuit interrupter, arc terminal means for establishing an arc, a casing defining a chamber within which the arc is established, said casing including a tubular member of insulating material, a tubular metal member lining said tubular member of insulating material internally from adjacent one end of the chamber to adjacent the middle thereof only, a second tubular metal member lining said tubular member of insulating material externally from adjacent the other end of the chamber to adjacent the middle thereof, each of said tubular metal members being substantially at the potential of one of said arc terminal means, and each of said tubular metal members having means for gripping said tubular member of insulating material adjacent the middle thereof and said arc terminal means causing the arc to be established adjacent the end of the chamber which is lined on the outside by said second tubular metal member.

ANDREW H. BAKKEN. 

